The present invention relates to a microwave oven, and more particularly, a device for preventing heat damage to an electric power cord for a microwave oven having a convectional cooking function.
Generally, the microwave oven is a cooking appliance which cooks foods by frictional heat generated by causing molecules of the foods to move at high speeds utilizing high frequency energy. Recently, there has been developed a convectional microwave oven having a cooking function characterized by a forced convection of hot air created by an electric heater and a blower fan in addition to the basic cooking function by high frequency energy. In such a conventional microwave oven, the cooking of foods such as meat and fish are boiled evenly from surface to interior by high frequency energy and at the same time, the surface of the foods is browned crispy by the heating of the hot air, so that the taste and flavor of foods are enhanced.
FIG. 5 illustrates a prior art convection microwave oven disclosed in Japanese Utility Model Publication No. 57-132118. As shown in FIG. 5, the prior art convection microwave oven has an inner case la forming a cooking chamber 1 and an outer case 6 surrounding the inner case 1a, wherein an electric component compartment(not shown) for mounting various electric components is located between the inner and outer cases 1a and 6. In the back of the cooking chamber 1, a duct 7a is provided between a rear plate 4a connected to the rear portion of the inner case 1a and the outer case 6 to form a hot air chamber 7 in which a blower fan 8 and an electric heater(not shown) are provided.
In an inner wall of the duct 7a, an insulating material 7b is fixed to prevent heat radiated from the heater from transferring backward. In the rear of the duct 7a, a cooling fan 8a, coaxially arranged with the blower fan 8, and a motor 8b for driving the cooling fan 8a and the blower fan 8 are provided. The duct 7a, the cooling fan 8a and the motor 8b are covered by a rear plate 6a connected to the rear portion of the outer case 6. The rear plate 6a has a plurality of air vents 9a and 9b for ventilating air by the operation of the cooling fan 8a.
In such a prior art convection microwave oven, high-temperature heat radiated from the heater and motor 8b are transferred to the rear of the microwave oven by the cooling fan 8a provided in the rear of the cooking chamber 1.
Therefore, in a convection cooking mode in which the electric heater is operated, the hot air chamber 7 located in the rear of the cooking chamber 1 and the rear plate 6a are relatively maintained at a high temperature. Further, as shown in FIG. 6, in the rear portion of the microwave oven, a power cord 2 for supplying the power to the microwave oven is provided. One end of the power cord 2 is fixed to the interior of the electric component compartment, and the other end having a plug 3 extends from the outer case 6 to the exterior and is inserted into a receptacle (not shown).
In such a microwave oven, however, the power cord 2 makes contact with highly heated elements and is apt to be damaged. That is, since the high-temperature heat emitted from the motor 8b and the heater located in the rear of the cooking chamber 1 is transferred to the rear plate 6a of the outer case 6, the power cord 2, which is movable freely, may touch the rear plate 6a and become damaged by its very high temperature. If such a contact often occurs, the life cycle of the power cord 2 is shortened and is apt to cause a short-circuit.